Integrated Assemblies Having Vertically-Spaced Channel Material Segments, and Methods of Forming Integrated Assemblies

ABSTRACT

Some embodiments include a NAND memory array having a vertical stack of alternating insulative levels and conductive levels. The conductive levels include control gate regions. High-k dielectric material is adjacent to the control gate regions and is configured as an arrangement of first vertically-extending linear segments which are vertically spaced from one another. Charge-blocking material is adjacent to the high-k dielectric material and is configured as an arrangement of second vertically-extending linear segments which are vertically spaced from one another. Charge-storage material is adjacent to the charge-blocking material and is configured as an arrangement of third vertically-extending linear segments which are vertically spaced from one another. Gate-dielectric material is adjacent to the charge-storage material. Channel material extends vertically along the stack and is adjacent to the gate-dielectric material. Some embodiments include integrated assemblies and methods of forming integrated assemblies.

TECHNICAL FIELD

Integrated assemblies (e.g., integrated NAND memory) havingvertically-spaced channel material segments, and methods of formingintegrated assemblies.

BACKGROUND

Memory provides data storage for electronic systems. Flash memory is onetype of memory, and has numerous uses in modern computers and devices.For instance, modern personal computers may have BIOS stored on a flashmemory chip. As another example, it is becoming increasingly common forcomputers and other devices to utilize flash memory in solid statedrives to replace conventional hard drives. As yet another example,flash memory is popular in wireless electronic devices because itenables manufacturers to support new communication protocols as theybecome standardized, and to provide the ability to remotely upgrade thedevices for enhanced features.

NAND may be a basic architecture of flash memory, and may be configuredto comprise vertically-stacked memory cells.

Before describing NAND specifically, it may be helpful to more generallydescribe the relationship of a memory array within an integratedarrangement. FIG. 1 shows a block diagram of a prior art device 1000which includes a memory array 1002 having a plurality of memory cells1003 arranged in rows and columns along with access lines 1004 (e.g.,wordlines to conduct signals WL0 through WLm) and first data lines 1006(e.g., bitlines to conduct signals BL0 through BLn). Access lines 1004and first data lines 1006 may be used to transfer information to andfrom the memory cells 1003. A row decoder 1007 and a column decoder 1008decode address signals AO through AX on address lines 1009 to determinewhich ones of the memory cells 1003 are to be accessed. A senseamplifier circuit 1015 operates to determine the values of informationread from the memory cells 1003. An I/O circuit 1017 transfers values ofinformation between the memory array 1002 and input/output (I/O) lines1005. Signals DQ0 through DQN on the I/O lines 1005 can represent valuesof information read from or to be written into the memory cells 1003.Other devices can communicate with the device 1000 through the I/O lines1005, the address lines 1009, or the control lines 1020. A memorycontrol unit 1018 is used to control memory operations to be performedon the memory cells 1003, and utilizes signals on the control lines1020. The device 1000 can receive supply voltage signals Vcc and Vss ona first supply line 1030 and a second supply line 1032, respectively.The device 1000 includes a select circuit 1040 and an input/output (I/O)circuit 1017. The select circuit 1040 can respond, via the I/O circuit1017, to signals CSEL1 through CSELn to select signals on the first datalines 1006 and the second data lines 1013 that can represent the valuesof information to be read from or to be programmed into the memory cells1003. The column decoder 1008 can selectively activate the CSEL1 throughCSELn signals based on the AO through AX address signals on the addresslines 1009. The select circuit 1040 can select the signals on the firstdata lines 1006 and the second data lines 1013 to provide communicationbetween the memory array 1002 and the I/O circuit 1017 during read andprogramming operations.

The memory array 1002 of FIG. 1 may be a NAND memory array, and FIG. 2shows a schematic diagram of a three-dimensional NAND memory device 200which may be utilized for the memory array 1002 of FIG. 1. The device200 comprises a plurality of strings of charge-storage devices. In afirst direction (Z-Z′), each string of charge-storage devices maycomprise, for example, thirty-two charge-storage devices stacked overone another with each charge-storage device corresponding to one of, forexample, thirty-two tiers (e.g., Tier0-Tier31). The charge-storagedevices of a respective string may share a common channel region, suchas one formed in a respective pillar of semiconductor material (e.g.,polysilicon) about which the string of charge-storage devices is formed.In a second direction (X-X′), each first group of, for example, sixteenfirst groups of the plurality of strings may comprise, for example,eight strings sharing a plurality (e.g., thirty-two) of access lines(i.e., “global control gate (CG) lines”, also known as wordlines, WLs).Each of the access lines may couple the charge-storage devices within atier. The charge-storage devices coupled by the same access line (andthus corresponding to the same tier) may be logically grouped into, forexample, two pages, such as P0/P32, P1/P33, P2/P34 and so on, when eachcharge-storage device comprises a cell capable of storing two bits ofinformation. In a third direction (Y-Y′), each second group of, forexample, eight second groups of the plurality of strings, may comprisesixteen strings coupled by a corresponding one of eight data lines. Thesize of a memory block may comprise 1,024 pages and total about 16 MB(e.g., 16 WLs×32 tiers×2 bits=1,024 pages/block, block size=1,024pages×16 KB/page=16 MB). The number of the strings, tiers, access lines,data lines, first groups, second groups and/or pages may be greater orsmaller than those shown in FIG. 2.

FIG. 3 shows a cross-sectional view of a memory block 300 of the 3D NANDmemory device 200 of FIG. 2 in an X-X′ direction, including fifteenstrings of charge-storage devices in one of the sixteen first groups ofstrings described with respect to FIG. 2. The plurality of strings ofthe memory block 300 may be grouped into a plurality of subsets 310,320, 330 (e.g., tile columns), such as tile column_(I), tile column_(j)and tile column_(K), with each subset (e.g., tile column) comprising a“partial block” of the memory block 300. A global drain-side select gate(SGD) line 340 may be coupled to the SGDs of the plurality of strings.For example, the global SGD line 340 may be coupled to a plurality(e.g., three) of sub-SGD lines 342, 344, 346 with each sub-SGD linecorresponding to a respective subset (e.g., tile column), via acorresponding one of a plurality (e.g., three) of sub-SGD drivers 332,334, 336. Each of the sub-SGD drivers 332, 334, 336 may concurrentlycouple or cut off the SGDs of the strings of a corresponding partialblock (e.g., tile column) independently of those of other partialblocks. A global source-side select gate (SGS) line 360 may be coupledto the SGSs of the plurality of strings. For example, the global SGSline 360 may be coupled to a plurality of sub-SGS lines 362, 364, 366with each sub-SGS line corresponding to the respective subset (e.g.,tile column), via a corresponding one of a plurality of sub-SGS drivers322, 324, 326. Each of the sub-SGS drivers 322, 324, 326 mayconcurrently couple or cut off the SGSs of the strings of acorresponding partial block (e.g., tile column) independently of thoseof other partial blocks. A global access line (e.g., a global CG line)350 may couple the charge-storage devices corresponding to therespective tier of each of the plurality of strings. Each global CG line(e.g., the global CG line 350) may be coupled to a plurality ofsub-access lines (e.g., sub-CG lines) 352, 354, 356 via a correspondingone of a plurality of sub-string drivers 312, 314 and 316. Each of thesub-string drivers may concurrently couple or cut off the charge-storagedevices corresponding to the respective partial block and/or tierindependently of those of other partial blocks and/or other tiers. Thecharge-storage devices corresponding to the respective subset (e.g.,partial block) and the respective tier may comprise a “partial tier”(e.g., a single “tile”) of charge-storage devices. The stringscorresponding to the respective subset (e.g., partial block) may becoupled to a corresponding one of sub-sources 372, 374 and 376 (e.g.,“tile source”) with each sub-source being coupled to a respective powersource.

The NAND memory device 200 is alternatively described with reference toa schematic illustration of FIG. 4.

The memory array 200 includes wordlines 202 ₁ to 202 _(N), and bitlines228 ₁ to 228 _(M).

The memory array 200 also includes NAND strings 206 ₁ to 206 _(M). EachNAND string includes charge-storage transistors 208 ₁ to 208 _(N). Thecharge-storage transistors may use floating gate material (e.g.,polysilicon) to store charge, or may use charge-trapping material (suchas, for example, silicon nitride, metallic nanodots, etc.) to storecharge.

The charge-storage transistors 208 are located at intersections ofwordlines 202 and strings 206. The charge-storage transistors 208represent non-volatile memory cells for storage of data. Thecharge-storage transistors 208 of each NAND string 206 are connected inseries source-to-drain between a source-select device (e.g., source-sideselect gate, SGS) 210 and a drain-select device (e.g., drain-side selectgate, SGD) 212. Each source-select device 210 is located at anintersection of a string 206 and a source-select line 214, while eachdrain-select device 212 is located at an intersection of a string 206and a drain-select line 215. The select devices 210 and 212 may be anysuitable access devices, and are generically illustrated with boxes inFIG. 4.

A source of each source-select device 210 is connected to a commonsource line 216. The drain of each source-select device 210 is connectedto the source of the first charge-storage transistor 208 of thecorresponding NAND string 206. For example, the drain of source-selectdevice 210 ₁ is connected to the source of charge-storage transistor 208₁ of the corresponding NAND string 206 ₁. The source-select devices 210are connected to source-select line 214.

The drain of each drain-select device 212 is connected to a bitline(i.e., digit line) 228 at a drain contact. For example, the drain ofdrain-select device 212 ₁ is connected to the bitline 228 ₁. The sourceof each drain-select device 212 is connected to the drain of the lastcharge-storage transistor 208 of the corresponding NAND string 206. Forexample, the source of drain-select device 212 ₁ is connected to thedrain of charge-storage transistor 208 _(N) of the corresponding NANDstring 206 ₁.

The charge-storage transistors 208 include a source 230, a drain 232, acharge-storage region 234, and a control gate 236. The charge-storagetransistors 208 have their control gates 236 coupled to a wordline 202.A column of the charge-storage transistors 208 are those transistorswithin a NAND string 206 coupled to a given bitline 228. A row of thecharge-storage transistors 208 are those transistors commonly coupled toa given wordline 202.

It is desired to develop improved NAND architecture and improved methodsfor fabricating NAND architecture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a prior art memory device having amemory array with memory cells.

FIG. 2 shows a schematic diagram of the prior art memory array of FIG. 1in the form of a 3D NAND memory device.

FIG. 3 shows a cross-sectional view of the prior art 3D NAND memorydevice of FIG. 2 in an X-X′ direction.

FIG. 4 is a schematic diagram of a prior art NAND memory array.

FIGS. 5 and 6 are diagrammatic cross-sectional side views of a region ofan integrated assembly shown at example sequential process stages of anexample method for forming an example NAND memory array.

FIG. 6A is a diagrammatic top view of a portion of the integratedassembly of FIG. 6.

FIGS. 7-19 are diagrammatic cross-sectional side views of the region ofthe integrated assembly of FIG. 5 shown at example sequential processstages of an example method for forming an example NAND memory array.The process stage of FIG. 7 may follow that of FIG. 6.

FIG. 19A is a diagrammatic top view of a portion of the integratedassembly of FIG. 19.

FIG. 20 is a diagrammatic cross-sectional side view of an integratedassembly showing a region of an example NAND memory array.

FIGS. 21-30 are diagrammatic cross-sectional side views of a region ofan integrated assembly shown at example sequential process stages of anexample method for forming an example NAND memory array. The processstage of FIG. 21 may follow that of FIG. 6.

FIGS. 31-40 are diagrammatic cross-sectional side views of a region ofan integrated assembly shown at example sequential process stages of anexample method for forming an example NAND memory array. The processstage of FIG. 31 is identical to that of FIG. 7.

FIG. 40A is a diagrammatic cross-sectional side view of an integratedassembly showing a region of an example NAND memory array at a processwhich may follow that of FIG. 40 in some embodiments.

FIG. 41 is a diagrammatic cross-sectional side view of an integratedassembly showing a region of an example NAND memory array at a processwhich may follow that of FIG. 40.

FIG. 41A is a diagrammatic cross-sectional side view of an integratedassembly showing a region of an example NAND memory array at a processwhich may follow that of FIG. 40A.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Operation of NAND memory cells comprises movement of charge between achannel material and a charge-storage material. For instance,programming of a NAND memory cell may comprise moving charge (i.e.,electrons) from the channel material into the charge-storage material,and then storing the charge within the charge-storage material. Erasingof the NAND memory cell may comprise moving holes into thecharge-storage material to recombine with the electrons stored in thecharge-storage material, and to thereby release charge from thecharge-storage material. The charge-storage material may comprisecharge-trapping material (for instance, silicon nitride, metal dots,etc.). A problem with conventional NAND can be that charge-trappingmaterial extends across multiple memory cells of a memory array, andsuch can lead to charge migration from one memory cell to another. Thecharge migration may lead to data retention problems. Some embodimentsinclude NAND architectures having breaks in the charge-trapping materialin regions between memory cells; and such breaks may advantageouslyimpede migration of charge between memory cells. Example embodiments aredescribed with reference to FIGS. 5-41.

Referring to FIG. 5, a construction (integrated assembly, integratedstructure) 10 includes a vertical stack 12 of alternating first andsecond levels 14 and 16. The first levels 14 comprise a first material60, and the second levels 16 comprise a second material 62. The firstand second materials may comprise any suitable compositions, and are ofdifferent compositions relative to one another. In some embodiments, thefirst material 60 may comprise, consist essentially of, or consist ofsilicon dioxide; and the second material 62 may comprise, consistessentially of, or consist of silicon nitride. The levels 14 and 16 maybe of any suitable thicknesses; and may be the same thickness as oneanother, or may be different thicknesses relative to one another. Insome embodiments, the levels 14 and 16 may have vertical thicknesseswithin a range of from about 10 nanometers (nm) to about 400 nm. In someembodiments, the levels 14 and 16 may have thicknesses within a range offrom about 10 nm to about 50 nm.

The stack 12 is shown to be supported over a base 18. The base 18 maycomprise semiconductor material; and may, for example, comprise, consistessentially of, or consist of monocrystalline silicon. The base 18 maybe referred to as a semiconductor substrate. The term “semiconductorsubstrate” means any construction comprising semiconductive material,including, but not limited to, bulk semiconductive materials such as asemiconductive wafer (either alone or in assemblies comprising othermaterials), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductor substrates described above. In some applications, the base18 may correspond to a semiconductor substrate containing one or morematerials associated with integrated circuit fabrication. Such materialsmay include, for example, one or more of refractory metal materials,barrier materials, diffusion materials, insulator materials, etc.

A gap is provided between the stack 12 and the base 18 to indicate thatother components and materials may be provided between the stack 12 andthe base 18. Such other components and materials may comprise additionallevels of the stack, a source line level, source-side select gates(SGSs), etc.

Referring to FIG. 6, an opening 64 is formed to extend through the stack12. The opening has sidewalls 65 extending along the first and secondmaterials 60 and 62.

FIG. 6A is a top view of a region of the assembly 10 at the processstage of FIG. 6, and shows that the opening 64 may have a closed shape(circular, elliptical, square or other polygonal, etc.) when viewed fromabove. In the illustrated embodiment, the opening 64 is circular whenviewed from above. The sidewalls 65 along the cross-section of FIG. 6are part of a continuous sidewall 65, as shown by the top view of FIG.6A. The sidewall 65 may be referred to as a peripheral sidewall of theopening, or as a peripheral sidewall surface of the opening. The terms“peripheral sidewall” and “peripheral sidewall surface” may be utilizedinterchangeably. The utilization of one term in some instances and theother in other instances may be to provide language variation withinthis disclosure to simplify antecedent basis within the claims thatfollow.

The opening 64 may be representative of a large number of substantiallyidentical openings formed at the process stage of FIGS. 6 and 6A andutilized for fabricating NAND memory cells of a NAND memory array. Theterm “substantially identical” means identical to within reasonabletolerances of fabrication and measurement.

Referring to FIG. 7, the first levels 14 are recessed relative to thesecond levels 16 along the sidewalls 65 of the opening 64. After therecessing, the second levels 16 have projecting terminal ends 66 whichextend beyond the recessed first levels 14. The terminal ends 66 havesurfaces 67 of the second material 62. The recessed first levels 14 havesurfaces 69 of the first material 60. Cavities (gaps) 68 are verticallybetween the terminal ends 66. The surfaces 69 may be considered to bealong inner edges of the cavities 68.

The surfaces 67 and 69 together form the peripheral sidewall surface 65of the opening 64 to be an undulating sidewall surface at the processstage of FIG. 7.

Referring to FIG. 8, the cavities 68 are filled with sacrificialmaterial 70. The sacrificial material 70 may comprise any suitablecomposition(s); and in some embodiments may comprise, consistessentially of, or consist of silicon (e.g., polycrystalline silicon).

The sacrificial material 70 has surfaces 71 along the sidewall 65 of theopening 64. In the illustrated embodiment, the surfaces 71 are formed tobe aligned with the surfaces 67 of the second material 62 to form theperipheral sidewall surface 65 of the opening 64 to be a substantiallystraight sidewall surface (and in the shown embodiment to extendsubstantially vertically). The term “substantially straight” meansstraight to within reasonable tolerances of fabrication and measurement,and the term “substantially vertically” means vertical to withinreasonable tolerances of fabrication and measurement.

Referring to FIG. 9, charge-blocking material 34 is formed along thesubstantially straight sidewall surface 65 (i.e., along the peripheralsidewall of the opening 64). The charge-blocking material 34 maycomprise any suitable composition(s); and in some embodiments maycomprise, consist essentially of, or consist of one or both of siliconoxynitride (SiON) and silicon dioxide (SiO₂).

The charge-blocking material 34 has a substantially flat topographyalong the substantially straight sidewall surface 65.

Referring to FIG. 10, charge-storage material 38 is formed adjacent thecharge-blocking material 34. The charge-storage material 38 may compriseany suitable composition(s). In some embodiments the charge-storagematerial 38 may comprise charge-trapping materials; such as, forexample, silicon nitride, silicon oxynitride, conductive nanodots, etc.For instance, in some embodiments the charge-storage material 38 maycomprise, consist essentially of, or consist of silicon nitride. Inalternative embodiments, the charge-storage material 38 may beconfigured to include floating gate material (such as, for example,polycrystalline silicon).

The charge-storage material 38 is formed along the flat topography ofthe charge-blocking material 34, and has a flat configuration in theillustrated embodiment of FIG. 10. The term “flat configuration” meansthat the material 38 is of substantially continuous thickness andextends substantially vertically straight, as opposed to beingundulating.

Gate-dielectric material (i.e., tunneling material, charge-passagematerial) 42 is formed adjacent the charge-storage material 38. Thegate-dielectric material 42 may comprise any suitable composition(s). Insome embodiments, the gate-dielectric material 42 may comprise, forexample, one or more of silicon dioxide, silicon nitride, siliconoxynitride, aluminum oxide, hafnium oxide, zirconium oxide, etc. Thegate-dielectric material 42 may be bandgap-engineered to achieve desiredelectrical properties; and accordingly may comprise a combination of twoor more different materials.

Channel material 44 is formed adjacent the gate-dielectric material 42,and extends vertically along the stack 12. The channel material 44comprises semiconductor material; and may comprise any suitablecomposition or combination of compositions. For instance, the channelmaterial 44 may comprise one or more of silicon, germanium, III/Vsemiconductor materials (e.g., gallium phosphide), semiconductor oxides,etc.; with the term III/V semiconductor material referring tosemiconductor materials comprising elements selected from groups III andV of the periodic table (with groups III and V being old nomenclature,and now being referred to as groups 13 and 15). In some embodiments, thechannel material 44 may comprise, consist essentially of, or consist ofsilicon.

Insulative material 46 is formed adjacent the channel material 44, andfills a remaining portion of the opening 64. The insulative material 46may comprise any suitable composition(s); and in some embodiments maycomprise, consist essentially of, or consist of silicon dioxide.

In the illustrated embodiment of FIG. 10, the channel material 44 isconfigured as an annular ring which surrounds the insulative material46. Such configuration of the channel material may be considered tocomprise a hollow channel configuration, in that the insulative material46 is provided within a “hollow” in the annular-ring-shaped channelconfiguration. In other embodiments (not shown), the channel materialmay be configured as a solid pillar configuration.

Referring to FIG. 11, the second material 62 (FIG. 10) is removed toleave voids 76. The voids 76 may be referred to as first voids todistinguish them from other voids which are formed at later processstages.

Referring to FIG. 12, high-k dielectric material 28 is formed within thefirst voids 76 (FIG. 11) to line the first voids, and then conductiveregions 22 are formed within the lined voids.

The term “high-k” means a dielectric constant greater than that ofsilicon dioxide. In some embodiments, the high-k dielectric material 28may comprise, consist essentially of, or consist of one or more ofaluminum oxide (AlO), hafnium oxide (HfO), hafnium silicate (HfSiO),zirconium oxide (ZrO) and zirconium silicate (ZrSiO); where the chemicalformulas indicate primary constituents rather than specificstoichiometries.

The high-k dielectric material 28 has a substantially uniform thicknessalong the interior peripheries of the voids 76 (FIG. 11), with the term“substantially uniform” meaning uniform to within reasonable tolerancesof fabrication and measurement. The high-k dielectric material 28 may beformed to any suitable thickness; and in some embodiments may be formedto a thickness within a range of from about 1 nm to about 5 nm.

The conductive regions 22 may comprise two or more conductive materials;and in the shown embodiment comprise a pair of conductive materials 24and 26. The conductive materials 24 and 26 may comprise any suitableelectrically conductive composition(s); such as, for example, one ormore of various metals (e.g., titanium, tungsten, cobalt, nickel,platinum, ruthenium, etc.), metal-containing compositions (e.g., metalsilicide, metal nitride, metal carbide, etc.), and/or conductively-dopedsemiconductor materials (e.g., conductively-doped silicon,conductively-doped germanium, etc.). The conductive materials 24 and 26are compositionally different from one another. In some embodiments thecore material 24 may comprise one or more metals (e.g., may comprisetungsten), and the outer conductive material 26 may comprise one or moremetal nitrides (e.g., may comprise titanium nitride).

In the shown embodiment, the high-k dielectric material 28 is directlyagainst the conductive material 26.

The levels 16 may be considered to be conductive levels at the processstage of FIG. 12, with such conductive levels comprising the conductiveregions 22.

The conductive regions 22 have front ends 78 facing thevertically-extending materials 34, 38, 42 and 44. The front ends 78 havefront surfaces 79 which also face the vertically-extending materials 34,38, 42 and 44. The conductive levels have upper surfaces (top surfaces)77 and lower surfaces (i.e., bottom surfaces) 81 which extend back fromthe front surfaces 79.

Referring to FIG. 13, the first material 60 (FIG. 12) is removed to formsecond voids 82.

Referring to FIG. 14, the sacrificial material 70 (FIG. 13) is removedto extend the second voids 82.

After the materials 60 (FIGS. 12) and 70 (FIG. 13) are removed, thehigh-k material 28 has exposed portions 84 along the upper and lowersurfaces 77 and 81 of the conductive regions 22.

Referring to FIG. 15, the exposed portions 84 (FIG. 14) of the high-kdielectric material 28 are removed to leave remaining portions 86 of thehigh-k dielectric material 28 along the front ends 78 of the conductiveregions 22. The remaining portions 86 of the high-k dielectric materialare configured as vertically-extending linear segments 88, with suchlinear segments being vertically-spaced from one another. In theillustrated embodiment of FIG. 15, the segments 88 are vertically-spacedfrom another by gaps along the second levels 14 (with such gaps beingportions of the voids 82). The segments 88 of the high-k dielectricmaterial 28 are directly against the front surfaces 79 of the conductiveregions 22, and are between such front surfaces and the charge-blockingmaterial 34. Notably, the high-k dielectric material 28 remains onlyalong the front surfaces 79 of the conductive regions 22, and does notwrap around the front ends 78 of the conductive regions 22 (i.e., thehigh-k dielectric material 28 does not extend along the top and bottomsurfaces 77 and 81 of the conductive regions 22).

The voids 82 may be considered to have a first vertical thickness T₁ atthe process stage of FIG. 15.

Referring to FIG. 16, strips 90 are formed within the second voids 82 tonarrow the second voids to a second vertical thickness T₂. The strips 90comprise strip material 92. The strip material 92 may comprise anysuitable composition(s). In some embodiments, the strips 90 comprisesacrificial material 92. Such sacrificial material may be electricallyinsulative or electrically conductive; and in some embodiments maycomprise, consist essentially of, or consist of silicon nitride. In someembodiment, the strips 90 may comprise insulative material 92 whichremains in a final construction.

Referring to FIG. 17, the second voids 82 are extended through thecharge-blocking material 34, and then are extended through thecharge-storage material 38. The extended voids 82 divide thecharge-blocking material 34 into vertically-spaced linear segments 36and divide the charge-storage material into vertically-spaced linearsegments 40. In some embodiments, the segments 88 of the high-kdielectric material 28 may be referred to as first segments, thesegments 36 of the charge-blocking material 34 may be referred to assecond segments, and the segments 40 of the charge-storage material 38may be referred to as third segments. In the shown embodiment, thesegments 36 of the charge-blocking material 34 are directly adjacent thesegments 88 of the high-k dielectric material 28; and the segments 40 ofthe charge-storage material 38 are directly adjacent the segments 36 ofthe charge-blocking material 34.

The front surfaces 79 of the conductive levels 22 have a first verticaldimension D₁, which may be considered to correspond to a thickness ofthe conductive regions 22 (or the conductive levels 16). The firstsegments 88 have a second vertical dimension D₂, the segments 36 have athird vertical dimension D₃, and the segments 40 have a fourth verticaldimension D₄. In the shown embodiment, the second vertical dimension D₂is about the same as the first vertical dimension D₁ (with the term“about the same” meaning the same within reasonable tolerances offabrication and measurement), the third vertical dimension D₃ is largerthan the second vertical dimension, and the fourth vertical dimension D₄is larger than the third vertical dimension. The relative sizes of thevertical dimensions D₁, D₂, D₃ and D₄ may be tailored by the thicknessesof the strips 90 (and in some embodiments, the strips 90 may be even beomitted); by the durations and compositions of the etches utilized topenetrate the various materials 28, 34 and 36; by the compositions ofthe materials 28, 34 and 36; etc.

It may be advantageous for the dimensions D₂, D₃ and D₄ to all be atleast about as large as the dimension D₁ of the front surfaces of theconductive regions 22 so that NAND memory cells (described below)utilize the full extents of the front surfaces of the conductiveregions. However, in some embodiments etching may reduce the verticaldimensions of one or more of the segments 88, 36 and 40 so that suchsegment(s) have vertical dimensions which are less than the verticaldimension D₁ of the front surfaces 79. In such embodiments, NAND memorycells may still be formed with suitable operational characteristics forsome applications.

In the illustrated embodiment of FIG. 17, the segments 36 and 40 havesubstantially flat configurations. Also, the channel material 44 has asubstantially flat configuration. The flat channel material maypositively impact string current as compared to non-flat configurations.Also, the flat segments 40 of the charge-storage material may have afavorable charge distribution.

The embodiment of FIG. 17 shows the voids 82 extending through thematerials 34 and 38, and stopping at the tunneling material 42. In otherembodiments, the voids 82 may be extended through the tunnelingmaterial.

Referring to FIG. 18, the strips 90 (FIG. 17) are removed.

Referring to FIG. 19, insulative material 56 is formed within the secondvoids 82 (FIG. 18). The insulative material 56 may comprise any suitablecomposition(s); and in some embodiments may comprise, consistessentially of, or consist of silicon dioxide. In the illustratedembodiment of FIG. 19, the insulative material 56 entirely fills thesecond voids 82 (FIG. 18).

The integrated assembly 10 of FIG. 19 may be considered to comprise astack of alternating insulative levels 14 and conductive levels 16.

The conductive levels 16 may be considered to be memory cell levels(also referred to herein as wordline levels) of a NAND configuration.The NAND configuration includes strings of memory cells (i.e., NANDstrings), with the number of memory cells in the strings beingdetermined by the number of vertically-stacked levels 16. The NANDstrings may comprise any suitable number of memory cell levels. Forinstance, the NAND strings may have 8 memory cell levels, 16 memory celllevels, 32 memory cell levels, 64 memory cell levels, 512 memory celllevels, 1024 memory cell levels, etc. The vertical stack 12 is indicatedto extend vertically beyond the illustrated region to show that theremay be more vertically-stacked levels than those specificallyillustrated in the diagram of FIG. 19.

NAND memory cells 52 comprise the dielectric barrier material 28,charge-blocking material 34, charge-storage material 38, gate-dielectricmaterial 42 and channel material 44. The illustrated NAND memory cells52 form a portion of a vertically-extending string of memory cells. Suchstring may be representative of a large number of substantiallyidentical NAND strings formed during fabrication of a NAND memory array(with the term “substantially identical” meaning identical to withinreasonable tolerances of fabrication and measurement).

Each of the NAND memory cells 52 includes a control gate region 54within a conductive level 16. The control gate regions 54 comprisecontrol gates analogous to those described above with reference to FIGS.1-4. The conductive levels 16 comprise regions 58 adjacent to, orproximate, the control gate regions 54. The regions 58 may be referredto as second regions, distal regions, or wordline regions.

FIG. 19A shows a top view of a region of the assembly 10 at theprocessing stage of FIG. 19, and shows that the various materials 28,34, 38, 42 and 44 may be configured as annular rings in some exampleembodiments.

In the embodiment of FIG. 19, the insulative levels 14 are entirelyfilled with the insulative material 56. In other embodiments, portionsof the voids 82 may remain within the insulative levels 14. Forinstance, FIG. 20 shows a configuration analogous to that of FIG. 19,but in which the voids 82 are only partially filled with the insulativematerial 56. Accordingly, portions of the voids 82 remain within theinsulative levels 14. The remaining portions of the voids 82 are cappedwith the insulative material 56. The voids 82 may be filled with air orany other suitable gas.

An advantage of the configuration of FIG. 20 (i.e., a configurationhaving voids within the insulative levels 14) is that such may alleviatecapacitive coupling between vertically-neighboring materials in theevent that such capacitive coupling is found to be problematic.

Another example process for fabricating NAND memory cells is describedwith reference to FIGS. 21-30.

Referring to FIG. 21, a construction (assembly) 10 a is shown at aprocess stage which may follow the process stage of FIG. 6. The high-kdielectric material 28 is formed as a layer 30 along the substantiallystraight sidewall surface 65 (i.e., along the peripheral sidewall of theopening 64), with the layer 30 extending through the stack 12.

Referring to FIG. 22, the charge-blocking material 34 is formed adjacentthe layer 30, the charge-storage material 38 is formed adjacent thecharge-blocking material 34, the gate-dielectric material (i.e.,tunneling material) 42 is formed adjacent the charge-storage material38, the channel material 44 is formed adjacent the gate-dielectricmaterial 42, and the insulative material 46 is formed adjacent thechannel material 44.

Referring to FIG. 23, the second material 62 (FIG. 22) is removed toleave the voids 76.

Referring to FIG. 24, the conductive regions 22 are formed within thevoids 76 (FIG. 23). The levels 16 may be considered to be conductivelevels comprising the conductive regions 22 at the process stage of FIG.24.

Referring to FIG. 25, the first material 60 (FIG. 24) is removed to formthe second voids 82. Regions of the high-k dielectric material areexposed by the second voids 82.

Referring to FIG. 26, the strips 90 are formed within the voids 82 tonarrow the voids 82. The narrowing of the voids 82 reduces an amount ofthe high-k dielectric material 28 exposed by the voids 82.

Referring to FIG. 27, the narrowed second voids 82 are extended throughthe high-k dielectric material 28 to form the vertically-stacked firstsegments 88 (i.e., the exposed regions of the high-k material 28 areremoved to form the segments 88). In the embodiment of FIG. 27, thesegments 88 have vertical dimensions D₂ which are greater than thevertical dimensions D₁ of the front surfaces 79 of the conductiveregions 22 (i.e., the front surfaces within the conductive levels 16).

Referring to FIG. 28, the narrowed voids 82 are extended through thecharge-blocking material 34, and then are extended through thecharge-storage material 38. The extended voids 82 divide thecharge-blocking material 34 into the vertically-spaced linear segments36 and divide the charge-storage material into the vertically-spacedlinear segments 40.

The embodiment of FIG. 28 shows the voids 82 extending through thematerials 34 and 38, and stopping at the tunneling material 42. In otherembodiments, the voids 82 may be extended through the tunnelingmaterial.

Referring to FIG. 29, the strips 90 (FIG. 28) are removed.

Referring to FIG. 30, the insulative material 56 is formed within thesecond voids 82 (FIG. 29). The assembly 10 a of FIG. 30 comprises NANDmemory cells 52 analogous to those described above with reference toFIG. 19.

Although the voids 82 (FIG. 29) are shown to be entirely filled with theinsulative material 56 at the process stage of FIG. 30, in otherembodiments the voids may be only partially filled to formconfigurations analogous to that described above with reference to FIG.20.

Another example process for fabricating NAND memory cells is describedwith reference to FIGS. 31-41.

Referring to FIG. 31, a construction (assembly) 10 b is shown at aprocess stage which may be identical to the process stage of FIG. 7. Theconstruction includes the opening 64 extending through the stack 12, andhaving the undulating peripheral sidewall surface 65. The cavities 68extend into regions of the peripheral surface 65.

Referring to FIG. 32, a layer of a material 94 is formed along theundulating surface 65. The material 94 may comprise any suitablecomposition(s); and in some embodiments may comprise, consistessentially of, or consist of silicon.

Referring to FIG. 33, the material 94 is partially oxidized to form anoxide 96 (e.g., silicon dioxide) laterally outward of the remainingmaterial 94. The remaining material 94 is within the cavities 68.

Referring to FIG. 34, the oxide 96 (FIG. 33) is removed. After the oxideis removed, the peripheral sidewall 65 of the opening 64 has anundulating surface that extends along the second material 62 and alongthe remaining material 94. In some embodiments, the undulating sidewallof the opening 64 at the process stage of FIG. 34 may be referred to asa second undulating sidewall to distinguish it from the first undulatingsidewall shown at the process stage of FIG. 31.

Referring to FIG. 35, the charge-blocking material 34 is formed alongthe undulating surface 65, the charge-storage material 38 is formedadjacent the charge-blocking material 34, the gate-dielectric material(i.e., tunneling material) 42 is formed adjacent the charge-storagematerial 38, the channel material 44 is formed adjacent thegate-dielectric material 42, and the insulative material 46 is formedadjacent the channel material 44. The materials 34, 38, 42 and 44 areall configured as vertically-extending layers which have undulatingtopographies substantially conformal to the undulating topography of theperipheral sidewall 65 of the opening 64.

Referring to FIG. 36, the second material 62 (FIG. 35) is removed toform the voids 76.

Referring to FIG. 37, the high-k dielectric material 28 is formed withinthe voids 76 (FIG. 36) to line the voids; and the conductive regions 22are formed within the lined voids 76. The levels 16 of FIG. 37 may bereferred to as conductive levels.

Referring to FIG. 38, the first material 60 (FIG. 37) is removed to formthe second voids 82. The material 94 is exposed within the second voids82.

Referring to FIG. 39, the material 94 (FIG. 38) is removed to extend thevoids 82.

Referring to FIG. 40, the voids 82 are extended through thecharge-blocking material 34, and then are extended through thecharge-storage material 38. The extended voids 82 divide thecharge-blocking material 34 into the vertically-spaced linear segments36, and divide the charge-storage material into the vertically-spacedlinear segments 40.

FIG. 40A shows a process stage which may be alternative to that of FIG.40. Exposed portions of the high-k dielectric material 28 are removedfrom along the upper and lower surfaces 77 and 81 of the conductiveregions 22 with processing analogous to that described above withreference to FIG. 15 to form the high-k dielectric material 28 into thevertically-extending linear segments 88.

Referring to FIG. 41, the construction 10 b is shown at a process stagesubsequent to that of FIG. 40. The insulative material 56 is formedwithin the voids 82 (FIG. 40). The assembly 10 b of FIG. 41 comprisesNAND memory cells 52 analogous to those described above with referenceto FIG. 19.

Although the voids 82 (FIG. 40) are shown to be entirely filled with theinsulative material 56 at the process stage of FIG. 41, in otherembodiments the voids may be only partially filled to formconfigurations analogous to that described above with reference to FIG.20.

Referring to FIG. 41A, the construction 10 b is shown at a process stagesubsequent to that of FIG. 40A. The insulative material 56 is formedwithin the voids 82 (FIG. 40A). The assembly 10 b of FIG. 41A comprisesNAND memory cells 52 analogous to those described above with referenceto FIG. 19. The segments 40 of the charge-storage material 38 haverounded configurations at the process stage of FIG. 41, in contrast tothe substantially flat configurations of such segments at theabove-discussed process stage of FIG. 19.

Although the voids 82 (FIG. 40A) are shown to be entirely filled withthe insulative material 56 at the process stage of FIG. 41A, in otherembodiments the voids may be only partially filled to formconfigurations analogous to that described above with reference to FIG.20.

In operation, the charge-storage material 38 may be configured to storeinformation in the memory cells 52 of the various embodiments describedherein. The value (with the term “value” representing one bit ormultiple bits) of information stored in an individual memory cell may bebased on the amount of charge (e.g., the number of electrons) stored ina charge-storage region of the memory cell. The amount of charge withinan individual charge-storage region may be controlled (e.g., increasedor decreased), at least in part, based on the value of voltage appliedto an associated gate 54, and/or based on the value of voltage appliedto the channel material 44.

The tunneling material 42 forms tunneling regions of the memory cells52. Such tunneling regions may be configured to allow desired migration(e.g., transportation) of charge (e.g., electrons) between thecharge-storage material 38 and the channel material 44. The tunnelingregions may be configured (i.e., engineered) to achieve a selectedcriterion, such as, for example, but not limited to, an equivalent oxidethickness (EOT). The EOT quantifies the electrical properties of thetunneling regions (e.g., capacitance) in terms of a representativephysical thickness. For example, EOT may be defined as the thickness ofa theoretical silicon dioxide layer that would be required to have thesame capacitance density as a given dielectric, ignoring leakage currentand reliability considerations.

The charge-blocking material 34 may provide a mechanism to block chargefrom flowing from the charge-storage material 38 to the associated gates54.

The dielectric-barrier material (high-k material) 28 may be utilized toinhibit back-tunneling of charge carriers from the gates 54 toward thecharge-storage material 38. In some embodiments, the dielectric-barriermaterial 28 may be considered to form dielectric-barrier regions withinthe memory cells 52.

The assemblies and structures discussed above may be utilized withinintegrated circuits (with the term “integrated circuit” meaning anelectronic circuit supported by a semiconductor substrate); and may beincorporated into electronic systems. Such electronic systems may beused in, for example, memory modules, device drivers, power modules,communication modems, processor modules, and application-specificmodules, and may include multilayer, multichip modules. The electronicsystems may be any of a broad range of systems, such as, for example,cameras, wireless devices, displays, chip sets, set top boxes, games,lighting, vehicles, clocks, televisions, cell phones, personalcomputers, automobiles, industrial control systems, aircraft, etc.

Unless specified otherwise, the various materials, substances,compositions, etc. described herein may be formed with any suitablemethodologies, either now known or yet to be developed, including, forexample, atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etc.

The terms “dielectric” and “insulative” may be utilized to describematerials having insulative electrical properties. The terms areconsidered synonymous in this disclosure. The utilization of the term“dielectric” in some instances, and the term “insulative” (or“electrically insulative”) in other instances, may be to providelanguage variation within this disclosure to simplify antecedent basiswithin the claims that follow, and is not utilized to indicate anysignificant chemical or electrical differences.

The terms “electrically connected” and “electrically coupled” may bothbe utilized in this disclosure. The terms are considered synonymous. Theutilization of one term in some instances and the other in otherinstances may be to provide language variation within this disclosure tosimplify antecedent basis within the claims that follow.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. Thedescriptions provided herein, and the claims that follow, pertain to anystructures that have the described relationships between variousfeatures, regardless of whether the structures are in the particularorientation of the drawings, or are rotated relative to suchorientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections, unless indicatedotherwise, in order to simplify the drawings.

When a structure is referred to above as being “on”, “adjacent” or“against” another structure, it can be directly on the other structureor intervening structures may also be present. In contrast, when astructure is referred to as being “directly on”, “directly adjacent” or“directly against” another structure, there are no interveningstructures present. The terms “directly under”, “directly over”, etc.,do not indicate direct physical contact (unless expressly statedotherwise), but instead indicate upright alignment.

Structures (e.g., layers, materials, etc.) may be referred to as“extending vertically” to indicate that the structures generally extendupwardly from an underlying base (e.g., substrate). Thevertically-extending structures may extend substantially orthogonallyrelative to an upper surface of the base, or not.

Some embodiments include an integrated structure having a vertical stackof alternating insulative levels and conductive levels. Channel materialextends vertically through the stack. The conductive levels have frontsurfaces facing the channel material, and have upper and lower surfacesextending back from the front surfaces. High-k dielectric material isarranged in vertically-stacked first segments. The high-k dielectricmaterial is along the front surfaces of the conductive levels and is notalong the upper and lower surfaces of the conductive levels.Charge-blocking material is arranged in vertically-stacked secondsegments. The second segments are adjacent the first segments.Charge-storage material is arranged in vertically-stacked thirdsegments. The third segments are adjacent the second segments.Gate-dielectric material is adjacent the charge-storage material, and isbetween the charge-storage material and the channel material.

Some embodiments include a NAND memory array having a vertical stack ofalternating insulative levels and conductive levels. The conductivelevels include control gate regions. High-k dielectric material isadjacent to the control gate regions and is configured as an arrangementof first vertically-extending linear segments which are verticallyspaced from one another. Charge-blocking material is adjacent to thehigh-k dielectric material and is configured as an arrangement of secondvertically-extending linear segments which are vertically spaced fromone another. Charge-storage material is adjacent to the charge-blockingmaterial and is configured as an arrangement of thirdvertically-extending linear segments which are vertically spaced fromone another. Gate-dielectric material is adjacent to the charge-storagematerial. Channel material extends vertically along the stack and isadjacent to the gate-dielectric material.

Some embodiments include a method of forming an integrated structure. Avertical stack is formed to include alternating first and second levels.The first levels comprise first material and the second levels comprisesecond material. An opening is formed to extend through the stack. Theopening has a peripheral sidewall. Charge-blocking material is formedadjacent to the peripheral sidewall. Charge-storage material is formedadjacent to the charge-blocking material. Gate-dielectric material isformed adjacent to the charge-storage material. Channel material isformed adjacent to the gate-dielectric material. The second material isremoved to leave first voids. Conductive levels are formed within thefirst voids. The conductive levels have front ends with front surfaces.The front surfaces face the charge blocking material. High-k dielectricmaterial is formed to be between the front surfaces and thecharge-blocking material. The high-k dielectric material is configuredas first segments which are vertically-spaced from one another, with thefirst segments being along the front surfaces of the conductive levelsand not wrapping around the front ends of the conductive levels. Thefirst material is removed to leave second voids. The second voids areextended through the charge-storage material to divide thecharge-storage material into vertically-spaced segments.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1-18. (canceled)
 19. A method of forming an integrated structure,comprising: forming a vertical stack of alternating first and secondlevels; the first levels comprising first material and the second levelscomprising second material; forming an opening to extend through thestack, the opening having a peripheral sidewall; forming charge-blockingmaterial adjacent the peripheral sidewall; forming charge-storagematerial adjacent the charge-blocking material; forming gate-dielectricmaterial adjacent the charge-storage material; forming channel materialadjacent the gate-dielectric material; removing the second material toleave first voids; forming conductive levels within the first voids; theconductive levels having front ends with front surfaces; the frontsurfaces facing the charge blocking material; forming high-k dielectricmaterial to be between said front surfaces and the charge-blockingmaterial; the high-k dielectric material being configured as firstsegments which are vertically-spaced from one another, with said firstsegments being along the front surfaces of the conductive levels and notwrapping around the front ends of the conductive levels; removing thefirst material to leave second voids; and extending the second voidsthrough the charge-storage material to divide the charge-storagematerial into vertically-spaced segments.
 20. The method of claim 19comprising forming the high-k dielectric material within the first voidsto line the first voids; wherein the forming of the conductive levelscomprises forming conductive material within the lined first voids;wherein the forming of the second voids exposes portions of the high-kdielectric material above and below the conductive material; wherein thesecond voids have a vertical thickness; and further comprising thefollowing steps in the following order; removing the exposed portions ofthe high-k dielectric material; forming strips within the second voidsto narrow said vertical thickness; extending the second voids throughthe charge-blocking material and then through the charge-storagematerial to divide the charge-storage material into thevertically-spaced segments; and at least partially filling the secondvoids with insulative material.
 21. The method of claim 19 comprisingforming the high-k dielectric material within the first voids to linethe first voids; wherein the forming of the conductive levels comprisesforming conductive material within the lined first voids; wherein theforming of the second voids exposes portions of the high-k dielectricmaterial above and below the conductive material; wherein the secondvoids have a vertical thickness; and further comprising; removing theexposed portions of the high-k dielectric material; forming sacrificialmaterial within the second voids to narrow said vertical thickness;after the vertical thickness is narrowed, extending the second voidsthrough the charge-blocking material and then through the charge-storagematerial to divide the charge-storage material into thevertically-spaced segments; removing the sacrificial material; and afterremoving the sacrificial material, at least partially filling the secondvoids with insulative material.
 22. The method of claim 21 wherein thesacrificial material comprises silicon nitride.
 23. The method of claim19 comprising: recessing the first levels relative to the second levelsto form cavities along the first levels; filling the cavities withsacrificial material to form the peripheral sidewall of the opening tohave a substantially straight sidewall surface; the forming of thecharge-blocking material comprising forming the charge-blocking materialalong the substantially straight sidewall surface; and removing thesacrificial material during the forming of the second voids.
 24. Themethod of claim 23 wherein the charge-blocking material has asubstantially flat topography along the substantially straight sidewallsurface; wherein the charge-storage material is formed along thesubstantially flat topography; and wherein each of the vertically-spacedsegments of the charge-storage material has a substantially flatconfiguration.
 25. The method of claim 23 wherein the sacrificialmaterial comprises polycrystalline silicon.
 26. The method of claim 19wherein: the high-k dielectric material is initially formed as a layerextending vertically through the stack; the removing of the firstmaterial exposes regions of the high-k dielectric material; and at leastportions of said regions are removed.
 27. The method of claim 26 whereinthe second voids have a vertical thickness, and further comprising thefollowing steps in the following order: forming strips within the secondvoids to narrow said vertical thickness and to reduce an amount of thehigh-k dielectric material which is exposed; removing the reduced amountof the exposed high-k dielectric material; and at least partiallyfilling the second voids with insulative material.
 28. The method ofclaim 26 wherein the second voids have a vertical thickness, and furthercomprising: forming sacrificial material within the second voids tonarrow said vertical thickness and to reduce an amount of the high-kdielectric material which is exposed; removing the reduced amount of theexposed high-k dielectric material; removing the sacrificial material;and after removing the sacrificial material, at least partially fillingthe second voids with insulative material.
 29. The method of claim 28wherein the sacrificial material comprises silicon nitride.
 30. Themethod of claim 19 comprising: recessing the first levels relative tothe second levels to form cavities along the first levels, and to form afirst undulating sidewall surface of the opening; forming a layer ofsilicon along the first undulating surface; partially oxidizing thelayer of silicon to form an oxide laterally outward of remainingsilicon; the remaining silicon being within the cavities; and removingthe oxide to form the peripheral sidewall of the opening to have asecond undulating surface extending along the remaining silicon andalong the second material of the second levels; wherein the forming ofthe charge-blocking material comprises forming the charge-blockingmaterial along the second undulating surface.
 31. The method of claim 30wherein the charge-blocking material has an undulating topography alongthe second undulating surface; wherein the charge-storage material isformed along the undulating topography of the charge-blocking material;and wherein each of the vertically-spaced segments of the charge-storagematerial has a rounded configuration.
 32. The method of claim 30comprising forming the high-k dielectric material within the first voidsto line the first voids; wherein the forming of the conductive levelscomprises forming conductive material within the lined first voids;wherein the forming the second voids exposes portions of the high-kdielectric material above and below the conductive material; and furthercomprising removing the exposed portions of the high-k dielectricmaterial.
 33. The method of claim 32 further comprising at leastpartially filling the second voids with insulative material.